Be sure to consider the impact on the peephole optimizer.  Also consider that adding volume inside the ceval.c loop may have unintended slowing effects on various compilers -- supposedly, this has been a serious issue in that past and there has been concern about growing the body of the loop.

I presume that the thrust of the efforts is directed at eliminating the an unpredictable switch branch inside the COMPARE_OP opcode.  If so, there's not much fat to be shed here.  The cost of the opcode switch is small relative the time it takes to dispatch to an object's rich comparison methods.